An arrangement of this kind, described in German Patent Disclosure Document DE-OS 31 25 434, has an endless band that is narrower than the rollers and is disposed such that it is displaceable parallel to the axis of the rollers. With this apparatus, in cases where relatively large ink-free zones are found on a plate in the circumferential direction, the disruptive influence of the damping medium that is transferred from these zones to the ink application rollers is supposed to be reduced.
In printing machines operating with ink and damping liquid, a number of problems arise, particularly when different subject matters are to be printed. Thus far, attempts have been made to solve these problems with individual provisions.
When ink and damping liquid are applied separately. the balance between these liquids is quite difficult to attain. It also takes a long time after the printing machine has been stopped before a state of balance is again attained. These disadvantages can be reduced by providing that at least part of the damping liquid be guided via an ink application roller to the plate cylinder. On the other hand, for instance in printing subject matters in which smaller zones that are to be printed alternate with larger, non-printed zones, it is more favorable to supply ink and damping liquid separately, because otherwise a change in the intensity of the ink color can take place because too much damping liquid is supplied. In order to meet these needs, it is already known to provide selectively engageable intermediate rollers between an ink application roller and a damping fluid application roller (see German Utility Model DE-GM 1 932 642).
When working with particularly absorbent paper, normal inkers sometimes do not print with a satisfactory color intensity. In that case it is advantageous to provide an additional ink transport train to an ink application roller (see German Patent Disclosure Document DE-OS 29 42 750).
If furthermore a subject matter to be printed has a section in the circumferential direction that prints over a relatively large surface area and requires a large amount of ink, and this section is adjoined by a non-printing section, the danger of random patterning exists. Inside the section printing over a large surface area, contours printed with an increased color intensity occur. This unattractive effect can be reduced by supplying additional ink from an ink reservoir to an application roller.
With an increasing buildup of emulsion, a pattern can also form on the damping fluid application roller, which then becomes apparent as random patterning on the printed material. The screwing down of a band can prevent the emulsion buildup and reduce the pattern forming on the roller to a minimum.